Method of forming blanks



UNITED STATES PATENT OFFICE METHOD OF FORMING BLANKB No Drawing.

, The present invention relates generally to improvements in the art of manufacturing certain types of metallic objects, and relates more specifically to a new and useful method of forming metal blanks directly from relatively unfinished material such as rod stock. An object of the invention is to provide an improved process of forming cap screw blanks or the like, directly from relatively crude rod stock, thereby materially reducing the cost of production by eliminating necessity of utilizing the more expensive drawn wire stock previously employed for such purposes. Another object of the invention is to provide an improved method of manufacturing cap screw or similar blanks, whereby successive blanks of accurate predetermined dimensions and of uniform and substantially identical structure may be produced. A further object of the invention is to provide a method of producing headed blanks, whereby the flow of metal during formation of the heads and shanks is maintained symmetrical with respect to the blank axes, and wherein no portion of the metal is overstressed.

The term rod stock as used herein, is intended to designate rod-like cylindrical bars of variable len h produced in the steel mills by merely rolhng heated billets into rods of an approximate diameter, these rods being subsequently pickled or otherwise treated to remove the scale. This rod stock is obtainable at relatively low cost and is also comparatively soft and hence readily workable, thus making its use in large quantities rather economical. The term wire stock as used herein, is intended to designate the product resulting from drawing rod stock While cold, through a die to accurate and uniform diameter. The stock thus produced is appreciably work hardened during the cold drawing operation, and the finished wire stock is also more expensive due to the cost of drawing, than the original rod stock.

It has heretofore been universal commercial practice in the cold heading industry, to utilize drawn wire stock in the formation of cap screw, bolt, and other types of headed blanks. During the formation of such blanks from drawn wlre stock, the wire is severed Application filed February 1, 1928. Serial No. 251,229.

into iec es of proper length, each-of which is su sequently deformed by means of suitable punches and dies, to provide an enlargement or head at one end and a shank at the opposite end. The heads of the blanks are produced by upsetting the ends of the severed pieces, thus providing enlargements which are far greater in transverse cross-section, than the original rod stock from which the wire stock has been drawn. When the blanks are of the type wherein a portion of the shank is of reduced diameter in order to permit subsequent application of rolled threads, the wire stock utilized in their formation may have a diameter, either substantially equal to that of the smallest final shank diameter, or substantially equal to that of the larger final shank diameter. When utilizing wire stock which is substantially equal in diameter to that of the smallest shank diameter, it is also necessary in the formation of the blanks, to upset the shank portion of each blank which is to have the greatest final diameter, at least up to or beyond the diameter of the original rod stock from which the wire has been drawn. When utilizing wire stock which is substantially equal in diameter to that of the larger shank diameter, it is necessary in the formation of the blanks, to draw down the portion of each blank to which the rolled thread is to be subsequently applied. It will be apparent that irrespective of the diameter of the wire stock employed in the production of the blanks in accordance with the prior methods, the work done in enlarging the wire stock to the original rod stock diameter when forming the head and when enlarging a shank portion, is Wasted effort and undesirably stresses and hardens the metal. The use of wire stock in the formation of the blanks in cases where a portion of the wire stock remains undeformed inv the final blank, also requires the provision of relatively accurately predetermined tolerences in order to enable the wire stock to be passed freely through the openings of the punches or dies without excessive clearance.

With the foregoing objections to the prior method of forming blanks in mind, it is the purpose of the present invention to provide quired to reduce the shank to accurate final diameter in cases where the final blanks have uniform shank diameter throughout, the metal of the shanks is not unduly stressed. The improved method also enables production of blanks wherein the junction between the heads and the shanks, is not over-stressed and in which the grain of the material at this junction may be gradually deflected to create a perfect union between the adjoining ortions of each blank. In forming the lanks by the improved method, the operations may be effected in one or more machines, as desired, and the heading operation may be accomplished either by single or multiple heading. In view of the fact that the extent of upsetting necessary under the improved process is materially reduced, the heading operation may ordinarily be accomplished in an effective manner by a single upset or head-' 0 ing blow.

A clear conception of the several steps of the improved method of forming blanks and of the manner in which the same may be performed, may be had from the accompanying description of one embodiment of the invention, the description being applied specifically to a method of forming ca screw or bolt blanks. It will be understoo however that the invention is also applicable to the manu- 40 facture of other types of blanks, wherein its adoption may prove beneficial and'more economical.

During exploitation of the present improved process of forming blanks, crude or previously undrawn rod stock which has been treated for the removal of scale and other undesirable coating, is severed or cut in- ,to pieces of suitable length, these pieces having the original rod stock diameter which is preferably slightly larger than that of the greatest shank diameter of the finished blank which it is desired to produce. When the finished blanks are to be provided with threads which are to extend along the entire length of the shank or unheaded portion thereof, the entire shank portion of each blank is forced through a suitable drawing die of well known form having an efiective drawing diameter equal to that desired in the final blank, thus reducing the entire shank to proper and accurate diameter in a single drawing operation and producing symmetrical flow lines which are slightly curved away from the blank axis at the shank end of the head. In case the finished blanks are to be provided with rolled threads extending along only a ortion of the shank length, each blank is ad itionally passed through a die of well known construction having a minor effective reducing diameter equal to that required for threading the blank, thus reducing the thread receiving portion of each blank to proper and accurate diameter and producing a union between the adjoining shank ortions wherein the grain or flow lines are li ewise symmetrical and gradually deflected. When the shank of each piece has been thus properly formed, the pieces are passed through a header wherein the heads may be formed in a well known manner. The heading and reducing operations may obviously be performed in one or a series of machines, the manner of performing the several steps being open to selection by themanufacturer.

From the foregoing description, it will be apparent that the present improvement enables or permits utilization of relatively crude rod stock for the production of accurately formed finished blanks having characteristics which are superior to those of the blanks produced with the method heretofore employed. The improved blanks may be manufactured at considerably lower cost, due principally to the decreased cost of the rolled rod stock as compared with that of the drawn wire stock heretofore used. The blanks produced by the improved method will obviously contain gradually distorted grain throughout their lengths, and the flow of the metal during the distorting operations will be uniform and symmetrical with respect to the blank axes, thereby producing blanks in which no portion of the metal is undesirably stressed. All of the metal of each blank is worked uniformly and the junctions between the head and shank portions are of maximum strength because of the gradual deflection of the rain at these junctions. Although the external appearance of the final product resulting from the improved method of manufacture, may not differ materially from that of the prior product, it will be evident that the physical properties of the new product are quite different and superior to those of .the previous blanks.

It will also be apparent that the successive blanks produced by the improved method will be of accurate dimensions and of uniform and substantially identical structure. The tolerance or clearance necessary in order to eliminate binding between the stock and the openings of the die, may be ignored-with the improved method, as no portion of the rod stock originally employed remains undistorted in' the finished-blank, as in the prior methods.

It should be understood that it isnot .desired to limit the present invention to the use of any specific type of apparatus or to the particular sequence in performance of the steps recited herein, for various modifications within the scope of the claims may occur to persons skilled in the art.

It is claimed and desired to secure by Letters Patent 1. The method of forming headed blanks, which comprises, severing previously undrawn rod stock of an approximate diameter transversely ofits grain into pieces, directly drawing a portion of each piece longitudinally of said grain to accurate finished diameter, and directly upsetting another portion of each piece to form a head.

2. The method of forming headed blanks,

which comprises, severing previously undrawn rolled rod stockof an approximate diameter transversely of its grain into pieces, directly drawing an end of each piece longitudinally of said grain to finished diameter, and subsequently directly upsetting the op posite end of each piece to form a head.

3. The method of forming headed blanks, which comprises, severing 1 previously undrawn rolled rod stock of an approximate diameter transversely of its grain into pieces, drawing a portion of each piece longitudinally of said grain to a definite diameter, drawing another portion of the previously drawn portion longitudinally of said grain to a reduced finished diameter, and upsetting another previously undrawn portion of each piece to form a head.

4. The method of forming headed blanks,

5 which comprises, severing elongated stock of greater diameter than the-finished blank shanks transversely into pieces, drawing a portion of each piece longitudinally to the largest diameter of the finished blank shank 40 while retaining the remainder of the piece at the original stock diameter, drawing a por-' tion of said previously drawn portion to a diameter less than the largest diameter of the finished shank portion to condition said last drawn portion for the rolling thereon of a thread which will merge with the adjacent end of said finished shank ortion, and directly enlarging said remain er to form a head.

In testimony whereof, the signature of the inventor is aflixed hereto.

RICHARD M. HEAMES. 

